Install Flatpak and Friends

Flatpak is a cross-distribution framework for
distribution and running of sandboxed applications.
XDG Desktop Portal provides Nuvola Apps with
desktop integration.
KDE Discover and GNOME Software make
the browsing and installation of Flatpaks easier.

All required packages are available in OpenSUSE repositories, run
following commands as root/sudo to install them:

Then restart your computer to add Flatpak paths alongside the system
ones. Otherwise, you may see strange errors. Unfortunately, just logging out
and logging in is not enough.

Add Flathub and Nuvola Apps Repositories

The Flathub repository provides GNOME Platform runtime, which is used by Nuvola to share common
dependencies with other Flatpak apps to reduce disk & memory usage. The Nuvola Apps repository
contains Nuvola Apps Service and individual Nuvola web apps.

KDE Plasma Workstation

KDE Discover may ask you for
an authentication to update the database of packages.

GNOME Workstation

Although GNOME Software can open Flatpak repository files
(*.flatpakrepo) directly since the version 3.22,
this feature
is currently broken in Leap 15.0 (it works in OpenSUSE Tumbleweed
though). You need to run following commands instead:

wget https://dl.flathub.org/repo/flathub.flatpakrepo

wget https://dl.tiliado.eu/flatpak/nuvola.flatpakrepo

gnome-software --local-filename flathub.flatpakrepo

gnome-software --local-filename nuvola.flatpakrepo

Finally, refresh the database of packages: Launch GNOME
Software → switch to the Updates screen
→ click the Refresh button in the top left corner.

Install Nuvola Apps Service

Nuvola Apps Service is an optional background service that provides individual Nuvola apps with
global shared resources such as a global configuration storage, global keyboard shortcuts, a HTTP remote control
server, and a command-line controller. While this service is optional, the installation is recommended.

KDE Plasma Workstation

In order to install Nuvola Apps Service with KDE Discover,
launch KDE Discover, search for Nuvola Apps Service and
finally click the Install button.

GNOME Workstation

In order to install Nuvola Apps Service with GNOME Software,
launch GNOME Software, search for Nuvola Apps Service and
finally click the Install button.

From Terminal

Alternatively, launch a Linux terminal emulator and run a following command: